As debates about energy grow more intense, Americans need dependable, objective, and authoritative energy information. The National Academies, advisers to the nation on science, engineering, and medicine, provide the facts about energy—a complex issue that affects us as individuals and as a nation.

Energy Defined

Quad

A unit of measure used to describe very large quantities of energy, such as the annual energy output of the United States. One quad is equal to one quadrillion—that is, one million billion, or 1015—Btu.